Synthesis, spectroscopic analysis, computational, antibacterial, antifungal, DNA binding and antioxidant activities of cobalt(II) and zinc(II) complexes of Mannich base ligand

Abstract

Biologically active small molecules of cobalt(II) and zinc(II) and complexes (MLX2⋅nH2O; M = Co(II) and Zn(II); X = Cl; n = 6 or 2) of Mannich base ligand (L) were synthesized from nicotinamide, formaldehyde and morpholine. The synthesized compounds were characterized by physicochemical, mass, proton NMR, FT-IR and UV–Visible and the results shows that the proposed structure of prepared complexes may be square planar geometry. It was further confirmed by the computational methods such as DFT calculation. Antimicrobial activities of prepared compounds were studied by well diffusion method and results shows that better antimicrobial activity at higher concentration and good activity against S. aureus and C. albicans. Antioxidant activity of prepared compounds were studied by free radical DPPH and results reveal that prepared compounds have better antioxidant activities. Moreover, DNA binding ability of prepared Co(II) and Zn(II) complexes with calf thymus DNA (CT-DNA) by UV–Visible spectroscopic method. The results have been suggested that prepared complexes can be interact with CT-DNA molecule through groove binding mode. Moreover, the binding constant of Co(II) complex (8.32 × 104 M−1) is higher than Zn(II) complex (1.20 × 104 M−1) correspondingly.